Change detection post-processors

The concept here is to be able to switch between different domain specific problems to solve.

• text_json_diff The traditional text and JSON comparison handler
• restock_diff Only cares about detecting if a product looks like it has some text that suggests that it's out of stock, otherwise assumes that it's in stock.

Some suggestions for the future

• graphical

API schema extension (api.yaml)

A processor can extend the Watch/Tag API schema by placing an api.yaml alongside its __init__.py. Define a components.schemas.processor_config_<name> entry and it will be merged into WatchBase at startup, making processor_config_<name> a valid field on all watch create/update API calls. The fully merged spec is served live at /api/v1/full-spec.

See restock_diff/api.yaml for a working example.

Todo

• Make each processor return a extra list of sub-processed (so you could configure a single processor in different ways)
• move restock_diff to its own pip/github repo